LM3402 datasheet(12/22 Pages) NSC

12 / 22 page

Application Information (Continued)

LOW POWER SHUTDOWN

The LM3402/02HV can be switched to a low power state

IN-SD = 90 µA) by grounding the RON pin with a signal-level

MOSFET as shown in Figure 3. Low power MOSFETs like

the 2N7000, 2N3904, or equivalent are recommended de-

vices for putting the LM3402/02HV into low power shutdown.

Logic gates can also be used to shut down the LM3402/

02HV as long as the logic low voltage is below the over

temperature minimum threshold of 0.3V. Noise filter circuitry

on the RON pin can cause a few pulses with a longer on-time

than normal after RON is grounded or released. In these

cases the OVP/OCP comparator will ensure that the peak

inductor or LED current does not exceed 300 mV / R

SNS.

THERMAL SHUTDOWN

Internal thermal shutdown circuitry is provided to protect the

IC in the event that the maximum junction temperature is

exceeded. The threshold for thermal shutdown is 165˚C with

a 25˚C hysteresis (both values typical). During thermal shut-

down the MOSFET and driver are disabled.

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FIGURE 2. Output Open Circuit Protection

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FIGURE 3. Low Power Shutdown

LM3402 Datasheet(PDF) 12 Page - National Semiconductor (TI)